In recent years, digital cameras have been widespread for converting an object image into an electric signal by using an imaging device such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, and digitizing and recording the electric signal.
A digital single-lens reflex camera includes a phase difference detection section for detecting the phase difference of the object image, and has a phase difference detection-type AF function of performing autofocus (hereinafter also referred to simply as “AF”). With the phase difference detection-type AF function, since it is possible to detect the direction of defocus and the amount of defocus, it is possible to shorten the amount of time required for moving the focus lens and focus quickly (e.g., Patent Document 1). For guiding light from an object onto the phase difference detection section, a conventional digital single-lens reflex camera includes a movable mirror that can be moved into/out of the optical path from the lens barrel to the imaging device.
A so-called compact digital camera employs an autofocus function by video AF using an imaging device (e.g., Patent Document 2). Thus, a compact digital camera realizes a small size by eliminating the mirror for guiding light from the object to the phase difference detection section. With such a compact digital camera, it is possible to autofocus while exposing the imaging device. That is, various operations using the imaging device, e.g., obtaining an image signal from the object image formed on the imaging device to display it on the image display section provided on the back of the camera or to record it in the recording section, can be performed while performing autofocus. The autofocus function by video AF is advantageous in that the precision is typically higher than phase difference detection-type AF.
Citation List
Patent Document
PATENT DOCUMENT 1: Japanese Published Patent Application No. 2007-163545
PATENT DOCUMENT 2: Japanese Published Patent Application No. 2007-135140